The purpose of this project is to implement myoelectric signals as a control source for an existing hand-grasp neuroprosthetic device. The current device uses a chest-mounted, shoulder position sensor. With the proposed device, control signals could be derived from weak myoelectric activity, making it possible for patients without sufficient shoulder mobility to use the neuroprosthesis. Myoelectric control is currently utilized in commercially available electromechanical prostheses. During the completed Phase I study, an electronic device was developed that records myoelectric signals and removes stimulation artifacts. A preliminary study was conducted with spinal-cord-injured and able-bodied subjects that demonstrated the feasibility of using myoelectric signals as a control source. During the proposed Phase II study, a pre-production device will be developed for myoelectric control of the neuroprosthesis. A clinical investigation will be conducted to demonstrate the utility of the myoelectric control system. The investigation participants will evaluate myoelectric control of their existing neuroprosthesis in daily use. It is anticipated that the participants will prefer myoelectric control due to improved durability, increased cosmetic appeal, and improved usability.